Most small aircraft have no emergency breathing apparatus. Because the small aircraft operate within ceilings in which air may be comfortably breathed, there are no special requirements for auxiliary breathing apparatus on such aircraft.
A potentially lethal situation may develop from an otherwise minor malfunction or minor emergency in an aircraft. A smoldering fire caused by a dropped cigarette or an electrical fire may produce noxious smoke. Carbon monoxide or fuel fumes or other nauseating or noxious fumes may fill an interior of an aircraft or at least a cockpit area.
The results are potentially lethal because, while an occupant of an automobile may simply pull the vehicle to the side of the road and alight, such an option does not exist for the pilot or his passengers. The plane must be flown to a safe landing area and landed. The highest of skills may be required in landing such a disabled aircraft at a time when the contaminating gaseous substances produce increased disability to the pilot. For example, exposure to carbon monoxide may slow reactions and cause drowsiness. Smoke may cause eye irritation and increasingly interfere with vision at the same time as breathing difficulties and coughing and choking increase. The result may be that a problem of initial minor nature may rapidly and geometrically increase to a major life-threatening problem because of the time required to escape from the surroundings and the inavailability of fresh air for breathing and washing fumes and gasses away from eyes.